free(): invalid next size (fast) in certain registers

[klinkigt]

Hi,

thank you for this tool. I recently came get the following problem, after it had been working for a while. As recommended I am making a:

pcr-oracle --from eventlog all --verify current

but this just leads to the problem:

Excluding PCR 10 from prediction (used by IMA)
free(): invalid next size (fast)
Abgebrochen (Speicherabzug geschrieben)

so trying to dig deeper I am going over those registers one by one:

pcr-oracle --from eventlog --before --stop-event grub-file=grub.cfg predict 0
sha256:0 d7f1b635cbf5ee8453ed92a1a41537a87a44018a6ca5cb562cec14f7ae081fbd

pcr-oracle --from eventlog --before --stop-event grub-file=grub.cfg predict 1
Error: Unable to extend PCR sha256:0: register was not initialized
free(): invalid pointer
Abgebrochen (Speicherabzug geschrieben)

pcr-oracle --from eventlog --before --stop-event grub-file=grub.cfg predict 2
Error: Unable to extend PCR sha256:0: register was not initialized
sha256:2 77e4f658f7b74581976910eb63f6ad085c13ddcd1031a546a3ac322306ad6def

which then continues like this. Said:

pcr-oracle --from eventlog all --verify current -d \
    --create-testcase /tmp/pcr-oracle.test

print a lot of stuff but also ends up in a:

8...xp..L.......E.e...~i.u.
:::         0640  92 9b f5 a6 bc 59 83 58                                                                         .....Y.X
:::   Firmware hashed entire event data
::: __pecoff_process_certificate_table: returning 2 cert blobs
::: Trying to extract signer's certificate from Authenticode cert
free(): invalid next size (fast)
Abgebrochen (Speicherabzug geschrieben)

No idea where the problem is. But at least the error for the free() seems not what should happen.

[Vogtinator]

If you can still reproduce this, please run it with valgrind.

[klinkigt]

Hi,

this is what I get with valgrind:

valgrind pcr-oracle --from eventlog all --verify current
==13445== Memcheck, a memory error detector
==13445== Copyright (C) 2002-2022, and GNU GPL'd, by Julian Seward et al.
==13445== Using Valgrind-3.22.0 and LibVEX; rerun with -h for copyright info
==13445== Command: pcr-oracle --from eventlog all --verify current
==13445== 
Excluding PCR 10 from prediction (used by IMA)
==13445== Invalid write of size 1
==13445==    at 0x11B21B: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x119251: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x10F632: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x4E721EF: (below main) (in /usr/lib64/libc.so.6)
==13445==  Address 0x55166d4 is 0 bytes after a block of size 20 alloc'd
==13445==    at 0x4845784: malloc (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==13445==    by 0x11B180: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x119251: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x10F632: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x4E721EF: (below main) (in /usr/lib64/libc.so.6)
==13445== 
==13445== Conditional jump or move depends on uninitialised value(s)
==13445==    at 0x484DAE8: rindex (in /usr/libexec/valgrind/vgpreload_memcheck-amd64-linux.so)
==13445==    by 0x111DE0: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x117A9F: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x119251: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x10F632: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x4E721EF: (below main) (in /usr/lib64/libc.so.6)
==13445== 
==13445== Use of uninitialised value of size 8
==13445==    at 0x111DE9: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x117A9F: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x119251: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x10F632: ??? (in /usr/bin/pcr-oracle)
==13445==    by 0x4E721EF: (below main) (in /usr/lib64/libc.so.6)
==13445== 
Fatal: Unable to open file /boot/efi/boot/grub2/grub.cfg: No such file or directory
==13445== 
==13445== HEAP SUMMARY:
==13445==     in use at exit: 4,451,348 bytes in 1,438 blocks
==13445==   total heap usage: 10,458 allocs, 9,020 frees, 5,133,678 bytes allocated
==13445== 
==13445== LEAK SUMMARY:
==13445==    definitely lost: 5,194 bytes in 62 blocks
==13445==    indirectly lost: 1,248,528 bytes in 114 blocks
==13445==      possibly lost: 0 bytes in 0 blocks
==13445==    still reachable: 3,197,626 bytes in 1,262 blocks
==13445==         suppressed: 0 bytes in 0 blocks
==13445== Rerun with --leak-check=full to see details of leaked memory
==13445== 
==13445== Use --track-origins=yes to see where uninitialised values come from
==13445== For lists of detected and suppressed errors, rerun with: -s
==13445== ERROR SUMMARY: 13 errors from 3 contexts (suppressed: 0 from 0)

is there a way to pass the correct path of the grub.cfg?

Best Martin

[Vogtinator]

Please try https://github.com/okirch/pcr-oracle/pull/53, that should fix the valgrind warnings.

https://github.com/okirch/pcr-oracle/pull/54 should fix the grub.cfg issue.